1. Field of the Invention
The present invention relates to an image processor and, more particularly, to a graphic edge extracting apparatus capable of extracting inner edge pixels of any painted graphic image at high speed.
2. Related Background Art
A conventional edge extracting apparatus for extracting an edge of a graphic image in an image processor uses a proper filter calculation 2 (FIG. 18 (2)) to calculate differences between a pixel of interest and adjacent pixels on an image plane 1 which is developed in an image memory, as shown in FIG. 18(1) and sequentially performs the filter calculation 2 of all the points on the image plane 1, thereby extracting boundary pixels 5 between a graphic image 3 and a non-graphic image portion 4 as an edge of the graphic image.
However, in the above conventional edge extracting apparatus, the edge boundary pixels 5 of the graphic image are obtained as an edge line. That is, pixels which actually form an edge of the graphic image are not extracted. Therefore, positions of the pixels which actually form the edge must be caluculated by coordinate values of the edge line. Especially, it is difficult to reconstruct an original perfect graphic image from the edge line. In addition, the filter calculation must be performed for each point on the image plane. Therefore, a pixel of interest and its adjacent pixels on the image plane must be repeatedly accessed, and their differences the differences between them); must be repeatedly calculated. As a result, calculation processing time is prolonged.